1. Field of the Invention
The present invention relates to developing devices, image forming apparatuses, image forming systems, and methods for manufacturing developing devices.
2. Description of the Related Art
(1) Image forming apparatuses such as laser beam printers are well known in the art. Such image forming apparatuses are provided with, for example, a photoconductor which is an example of an image bearing body for bearing a latent image, and a developing device for developing, with a developer, the latent image borne on the photoconductor. When the image forming apparatus receives image signals etc. from an external device such as a host computer, it positions the developing device at a developing position which is in opposition to the photoconductor, develops the latent image borne on the photoconductor with the developer in the developing device to form a developer image, and transfers the developer image onto a medium to ultimately form an image on the medium.
In order to achieve, for example, the above-described function of developing the latent image borne on the photoconductor, the developing device of the above-described type is provided with a housing that is for containing the developer and that has an opening, and a developing roller, which is an example of a developer bearing roller, that is for bearing the developer and that is provided facing the opening. The developing device develops the latent image borne on the photoconductor with the developer borne on the developing roller.
The developing device of the above-described type is also provided with a sealing member that abuts against the developing roller to prevent the developer from spilling. The sealing member and the developing roller are supported by a supporting member, and the supporting member is attached to the housing.
The developing device of the above-described type is also provided with an urging member for urging the sealing member toward the developing roller. The urging member presses the sealing member against the developing roller by urging the sealing member toward the developing roller with its urging force. (See, for example, JP 2003-280371 A.)
By the way, in order for the sealing member to appropriately achieve its function of preventing the developer from spilling, it is necessary to make the abutting pressure at which the sealing member abuts against the developing roller even. In order to do so, it is necessary to appropriately set the position of the urging member, for example, the relative position of the urging member with respect to the developing roller, the sealing member, and a member against which the urging member abuts on the opposite side from the sealing member, to a desired position.
Meanwhile, a conventional developing device having an urging member for urging the sealing member toward the developing roller is known to have an urging member provided between a sealing member and a housing. In such a case, in order to appropriately set the relative position of the urging member with respect to the developing roller, the sealing member, and the housing to a desired position, it is necessary to strictly control the positional relationship between the supporting member that supports the developing roller and the sealing member, and the housing to which the supporting member is attached.
Therefore, in such a developing device, there are problems in that it is difficult to carry out appropriate positioning of the relative position of the urging member with respect to the developing roller, the sealing member, and the housing, and thus, it is difficult to make the abutting pressure of the sealing member against the developing roller even.
(2) Another type of image forming apparatus is provided with, for example, a photoconductor which is an example of an image bearing body for bearing a latent image, and a developing device for developing, with a developer, the latent image borne on the photoconductor. When the image forming apparatus receives image signals etc. from an external device such as a host computer, it positions the developing device at a developing position which is in opposition to the photoconductor, develops the latent image borne on the photoconductor with the developer in the developing device to form a developer image, and transfers the developer image onto a medium to ultimately form an image on the medium.
In order to achieve, for example, the above-described function of developing the latent image borne on the photoconductor, the developing device of the above-described type is provided with: a housing that is for containing the developer and that has an opening; a developing roller, which is an example of a developer bearing roller, that is for bearing the developer and that is provided facing the opening; and a restriction blade that is an example of a layer-thickness restricting member that abuts against the developing roller along its axial direction to restrict a thickness of a layer of the developer. The developing device restricts the thickness of the layer of developer borne on the developing roller using the restriction blade, and develops the latent image borne on the photoconductor with the developer whose layer thickness has been restricted.
The developing device of the above-described type is also provided with a first sealing member that abuts against the developing roller along the axial direction thereof to prevent the developer from spilling, and a second sealing member that abuts against an end, in the axial direction, of the developing roller along the circumferential direction of the developing roller to prevent the developer from spilling. (See, for example, JP 2003-280371 A.)
In order for the restriction blade to appropriately achieve its function of restricting the layer thickness of the developer as described above, it is necessary to set the relative position of the restriction blade with respect to the developing roller to an appropriate position with high precision. Also, in order for the first sealing member and the second sealing member to appropriately achieve their function of preventing the developer from spilling as described above, it is necessary to set the relative position of the first sealing member and the second sealing member with respect to the developing roller to an appropriate position with high precision.
Incidentally, as conventional developing devices provided with a developing roller, a restriction blade, a first sealing member, and a second sealing member, there are known developing devices having those members attached either directly, or via a supporting member corresponding to each of those members, to the housing. However, in assembling such a developing device, it is necessary to assemble these members to the housing while adjusting these members such that the relative positions of the restriction blade, the first sealing member, and the second sealing member with respect to the developing roller are appropriately set. Such tasks are extremely burdensome.
(3) Another type of image forming apparatus is provided with, for example, a photoconductor which is an example of an image bearing body for bearing a latent image, and a developing device for developing, with a developer, the latent image borne on the photoconductor. When the image forming apparatus receives image signals etc. from an external device such as a host computer, it positions the developing device at a developing position which is in opposition to the photoconductor, develops the latent image borne on the photoconductor with the developer in the developing device to form a developer image, and transfers the developer image onto a medium to ultimately form an image on the medium.
In order to achieve, for example, the above-described function of developing the latent image borne on the photoconductor, the developing device of the above-described type is provided with a housing that is for containing the developer and that has an opening, and a developing roller, which is an example of a developer bearing roller, that is for bearing the developer and that is provided facing the opening. The developing device develops the latent image borne on the photoconductor with the developer borne on the developing roller.
The developing device of the above-described type is also provided with a sealing member for preventing the developer from spilling from the housing. The sealing member is supported in a bent state on the side of one end in the lateral direction thereof by the developing device, and abuts against the developer bearing roller on the side of the other end in the lateral direction thereof. (See, for example, JP 2003-280371 A.)
In a situation in which the sealing member is supported in a bent state on the side of one end in the lateral direction thereof by the developing device and in which the sealing member abuts against the developer bearing roller on the side of the other end in the lateral direction thereof, the abutment of the sealing member against the developer bearing roller may become inappropriate due to how the sealing member bends. Examples in which the abutment becomes inappropriate are cases where the lateral-direction width of abutment of the sealing member is too short, or where the abutting pressure of the sealing member is uneven. Such an inappropriate abutment may cause deterioration in the function of the sealing member of preventing the developer from spilling.
(4) Another type of image forming apparatus is provided with, for example, an image bearing body for bearing a latent image, and a developing device that develops the latent image borne on the image bearing body with a developer. When the image forming apparatus receives image signals etc. from an external device such as a host computer, the developing device is positioned in a developing position which is in opposition to the image bearing body, the latent image borne on the image bearing body is developed with the developer contained in the developing device to form a developer image, and the developer image is transferred onto a medium to ultimately form an image on the medium.
The developing device of the type described above has, for example, a housing that is for containing the developer and that has an opening, and a developer bearing roller that is for bearing the developer and that is provided facing the opening.
In such a developing device, an end sealing member is provided between the housing and the developer bearing roller for preventing the developer from spilling from the ends of the developer bearing roller. The end sealing member prevents the developer from spilling by applying a pressure (which is referred to also as “abutting pressure” below) against the developer bearing roller. (See, for example, JP 2003-295609 A.)
In such developing devices, it is necessary to set the abutting pressure to a suitable value. This is because the function of preventing the developer from spilling becomes insufficient if the abutting pressure is small, whereas the torque required for rotating the developer bearing roller becomes large if the abutting pressure is large.
In some cases, however, it is not possible to apply an abutting pressure of a suitable value, depending on the relationship between the width of the end sealing member and the width of a sealing space between the housing and the developer bearing roller where the end sealing member is provided. For example, the abutting pressure will become larger than a suitable value if the relationship between the width of the sealing space and the width of the end sealing member makes the compression amount of the end sealing member between the housing and the developer bearing roller become larger than a predetermined compression amount.